There are snakes in Panama that are beautiful, snakes that are rare, snakes that are completely harmless and snakes that you probably do not want to accidentally step on.
Then there is the fer de lance.
Known scientifically as Bothrops asper, and commonly called the terciopelo or equis in parts of Central America, the fer de lance is the snake that has earned the greatest reputation among people who actually spend time in the Panamanian countryside. It is not simply a scary looking snake. It is large, extremely well camouflaged, widely distributed, equipped with a powerful venom and perfectly capable of living in the same landscapes where people work, farm and walk.
That combination is what makes it so dangerous.
The fer de lance is responsible for the vast majority of snakebites in Panama, and scientific research describes it as the most medically important venomous snake in Central America. Panama also has one of the highest rates of snakebite envenoming in Latin America.
For anyone hiking, camping, working outdoors or exploring rural Panama, learning about this snake is considerably more useful than simply being afraid of it.
Because the most frightening thing about a fer de lance is not that it wants to bite you.
It is that you might not know it is there.
What Exactly Is a Fer de Lance?
The fer de lance is a member of the pit viper family. Its scientific name is Bothrops asper, and it is found from parts of southern Mexico through Central America and into northern South America.
In Panama, you may hear several different names for it. Fer de lance is the name most familiar to international visitors. Terciopelo is widely used elsewhere in Central America, while equis is a common name in Panama because of the distinctive dark markings along its body.
The name fer de lance comes from French and means "spearhead," a reference to the broad, triangular shape of its head.
And that head is one of the first things that makes the snake look different from the harmless snakes you may encounter in Panama.
The head is broad and distinctly triangular, while the neck is relatively narrow. The snake also has the characteristic vertical pupils of a viper and heat sensing pits between its eyes and nostrils.
Those pits are not decorative.
They are sophisticated biological heat sensors.
The Fer de Lance Can Detect Heat
Like other pit vipers, the fer de lance has specialized heat sensing organs between its eyes and nostrils.
These allow it to detect infrared radiation produced by warm objects.
In practical terms, this means that a warm blooded animal moving nearby can produce a detectable thermal signal even when visibility is poor.
Imagine having a built in thermal imaging system.
That is essentially part of the equipment this snake carries around with it.
It is particularly useful for a nocturnal ambush predator because rodents and other potential prey can be detected even when they are difficult to see.
This is one reason the fer de lance can be such an effective hunter in dense vegetation.
Its Camouflage Is Almost Ridiculous
This is probably the most important thing for anyone walking through the Panamanian jungle to understand.
The fer de lance can be incredibly difficult to see.
Its body is covered in complex brown, tan, gray and darker markings that can blend into dead leaves, branches, soil, roots and forest debris.
A snake lying completely still on a jungle trail may look exactly like part of the forest floor.
And unlike a brightly colored coral snake, it does not advertise itself.
It disappears.
That is one of the reasons accidental encounters are such a problem.
You can walk past a snake without ever realizing it was there.
You can step beside one.
You can reach down beside a fallen log.
You can put your hand into vegetation.
And suddenly the situation changes.
It Is Not Hunting People
Despite its reputation, the fer de lance is not wandering around the jungle looking for humans to attack.
This is an important distinction.
The snake is primarily interested in finding food and avoiding unnecessary danger. Like most wild snakes, it would generally rather not waste energy fighting something as large as a human.
The problem is that humans and fer de lances frequently occupy the same environments.
Scientific research has found that Bothrops asper is not restricted to untouched rainforest. It can adapt to disturbed environments, agricultural areas and places close to human habitation.
That is where the danger increases.
A snake that lived exclusively in deep, inaccessible rainforest would have fewer opportunities to encounter people.
The fer de lance is not that kind of snake.
Why Does It Live Around Farms?
The answer is food.
Where there are farms, plantations and human settlements, there are often rodents.
Where there are rodents, there is an excellent food supply for a snake that specializes in ambush hunting.
This creates an unfortunate ecological chain.
People cultivate crops.
Rodents find food.
Fer de lances find rodents.
Humans find fer de lances.
And nobody is particularly happy about the arrangement.
This ability to live in altered environments is one of the major reasons Bothrops asper causes so many snakebites across Central America. Researchers studying Panama have specifically noted its presence in agricultural fields and near human dwellings.
The Fer de Lance Is an Ambush Predator
The fer de lance does not need to chase prey through the jungle.
It has a much more efficient strategy.
It waits.
A snake can position itself near a trail used by rodents or beside vegetation where prey is likely to pass. It remains incredibly still, sometimes becoming almost indistinguishable from its surroundings.
Then something comes close.
The snake strikes.
The fangs penetrate.
Venom is delivered.
And the snake releases its prey.
This is a remarkably efficient hunting strategy.
It also explains why simply walking faster through the forest is not necessarily safer.
The snake does not care how quickly you are moving.
It cares whether you are close enough.
Those Fangs Are Serious Weapons
As a pit viper, the fer de lance has long, hinged venom injecting fangs.
The fangs are normally folded back against the roof of the mouth.
When the snake strikes, they rotate forward.
This allows the snake to deliver venom deeply into tissue.
And Bothrops asper is capable of delivering a substantial venom dose.
That is one reason bites can become extremely serious.
The danger isn't simply the possibility of death.
A severe bite can cause enormous local tissue damage and potentially permanent disability.
What Makes Its Venom So Dangerous?
This is where the fer de lance becomes considerably more frightening than its appearance alone would suggest.
Panamanian Bothrops asper venom has been shown to have hemorrhagic, myotoxic, edema forming, defibrinating and coagulant activities, as well as proteolytic and phospholipase activity.
In ordinary language, this means the venom can attack the body in several different ways.
It can damage tissue.
It can cause massive swelling.
It can damage muscle.
It can interfere with the blood clotting system.
It can cause bleeding.
And severe envenoming can produce systemic complications including low blood pressure, kidney injury and potentially life threatening organ damage.
That combination is what makes the fer de lance such a medically important snake.
The Bite Can Become Much Worse Over Time
One frightening characteristic of a serious fer de lance bite is that the damage is not necessarily finished when the snake disappears.
Pain and swelling can progress.
Bruising can spread.
Bleeding and tissue damage can develop.
In severe cases, extensive local tissue destruction can lead to permanent damage.
This is why snakebite is not something where you should think, "It doesn't look too bad, so I'll see how I feel tomorrow."
A suspected venomous snakebite is a medical emergency.
Get professional medical care immediately.
Panama Has a Remarkable Amount of Snakebite Research
Panama is an important place for studying fer de lance venom because the snake is so medically significant here.
Researchers have actually compared venom from fer de lances collected in different parts of Panama, including Bocas del Toro, Chiriquí, Veraguas, Coclé, Panama and Darién.
Interestingly, the venoms showed broadly similar toxicological profiles, although there were some quantitative differences, particularly in myotoxicity.
So a fer de lance from Chiriquí and one from the Caribbean side of Panama are not completely different animals with completely different venom.
They are regional populations of the same species with broadly similar medical significance.
The Fer de Lance Is Surprisingly Adaptable
One of the most interesting facts about this snake is how successful it is.
It does not require pristine rainforest.
It can live in primary forest, secondary forest, agricultural landscapes and other disturbed habitats.
That adaptability is one of the reasons it has become such an important snake in Panama.
Many wild animals struggle when humans change their habitat.
The fer de lance has found a way to benefit from some of those changes.
More rodents.
More suitable hiding places.
More edges between forest and open land.
More opportunities to encounter people.
From the snake's perspective, it is simply taking advantage of the environment.
From a human perspective, it is a little less convenient.
It Is Mostly a Nighttime Snake
Fer de lances are particularly active at night.
That makes sense when you consider their prey and their heat sensing abilities.
A warm rodent moving through vegetation in darkness is exactly the kind of target that a pit viper is designed to detect.
This is one reason nighttime jungle walks require extra attention.
A snake that was relatively inactive during the heat of the day may become much more active after sunset.
And because its camouflage works extremely well against leaves and soil, using a flashlight is important.
Look where you are putting your feet.
Look beside logs.
Look along the edges of trails.
And don't blindly reach into holes or piles of vegetation.
They Can Swim
Another interesting fact that surprises many people is that fer de lances are capable swimmers.
This should not be interpreted as "there are venomous snakes waiting for you in every Panamanian river."
There aren't.
But it is another reminder that their habitat is not limited to dry forest floor.
They are highly adaptable animals and can move through wet environments.
This is particularly relevant in a country like Panama, where rivers, streams, wetlands and tropical forest are everywhere.
They Are Excellent Climbers Too
The fer de lance is primarily associated with the ground, but it is capable of climbing.
This is another reason not to assume that a snake must be sitting directly on the trail.
Young snakes in particular may use vegetation more frequently than large adults.
The forest is a three dimensional environment.
If you are hiking through Panama, don't develop the habit of thinking that all snakes will be six inches in front of your boots.
They can be elsewhere.
The Females Can Produce a Lot of Babies
Another reason the species is so successful is reproduction.
Female fer de lances can produce large litters of live young rather than laying eggs.
The number of offspring can vary considerably, but large broods have been documented.
That means one successful female can potentially introduce a surprisingly large number of young snakes into an area.
And the babies are not harmless simply because they are small.
A common myth about venomous snakes is that young snakes are more dangerous because they supposedly cannot control how much venom they inject.
The reality is more complicated. Juveniles can certainly deliver venom and should be treated as medically significant, but the old idea that every baby viper automatically injects its entire venom supply is an oversimplification.
The safest approach is much simpler.
Small fer de lance?
Stay away.
Large fer de lance?
Stay even farther away.
The "X" on Its Back Is Where the Name Equis Comes From
If you ever hear a Panamanian talking about an "equis," they may be referring to the fer de lance.
The dark geometric markings along the body can form patterns resembling the letter X.
These markings are part of its camouflage and can make the snake surprisingly difficult to identify when it is sitting among leaves and branches.
Ironically, the pattern that helps you recognize the snake when you see a photograph can make it harder to notice when it is lying in the jungle.
Nature has a sense of humor.
Why Is It Considered Panama's Most Feared Snake?
There are several reasons.
First, it is widespread.
Second, it can live close to people.
Third, it is well camouflaged.
Fourth, it is capable of delivering a medically serious venom.
Fifth, it accounts for a huge proportion of snakebite cases.
And sixth, people who work outdoors have a much greater chance of encountering one than they would some rare rainforest snake.
A study of snakebites in Veraguas found that Bothrops asper was responsible for 43.8 percent of recorded cases during the study period, with most bites occurring during the rainy season. Hands, feet and toes accounted for nearly three quarters of bite locations.
That last statistic tells you something important.
A lot of snakebite prevention is really about where humans put their hands and feet.
Rainy Season Is Particularly Important
The rainy season changes the behavior and movement of both humans and snakes.
Vegetation becomes thicker.
Trails become wetter.
People work differently in fields.
Animals move around differently.
And snakebite studies in Panama have found a strong association between bites and the rainy season.
This doesn't mean you should be terrified every time it rains.
It means that if you spend a lot of time hiking, farming, camping or working outdoors during the wet season, you should become more deliberate about where you step and where you put your hands.
What Should You Do If You See One?
The best response is incredibly boring.
Stop.
Back away.
Give it space.
Do not try to kill it.
Do not try to catch it.
Do not poke it with a stick.
Do not take a selfie beside it.
And definitely do not attempt to prove to your friends that you are brave.
The snake does not care about your reputation.
If it has an escape route, let it use it.
Most snake encounters end perfectly well when both parties are allowed to go in opposite directions.
What If You Are Bitten?
This is the one part of the article where there is no room for joking.
A suspected fer de lance bite requires urgent medical attention.
Get to a hospital or appropriate medical facility as quickly and safely as possible.
Do not attempt to suck out the venom.
Do not cut the wound.
Do not apply a tourniquet unless specifically directed by trained medical professionals.
Do not try to capture or kill the snake.
If it can be safely identified from a distance, a photograph may help, but do not risk another bite trying to obtain one.
Antivenom is an important part of medical treatment for serious Bothrops envenoming, and research on Panamanian fer de lance venom has found that polyvalent antivenom used in the region can neutralize the lethal activity of venom from populations sampled across Panama.
The important thing is getting professional treatment quickly.
The Fer de Lance Is Not a Monster
For all the fear surrounding this snake, it is worth remembering that the fer de lance is an extraordinary animal.
It is a highly specialized predator.
It has heat sensing organs.
It has sophisticated venom.
It has remarkable camouflage.
It can survive in changing environments.
It can detect and ambush prey with incredible efficiency.
And it plays an important role in controlling populations of rodents and other small animals.
The problem is not that the snake is evil.
The problem is that its evolutionary equipment is extremely effective at doing something humans would rather it didn't do.
Why Panama's Fer de Lance Deserves Respect
There are plenty of reasons to be fascinated by the fer de lance.
It is one of the most important venomous snakes in Panama.
It is one of the country's most medically significant wild animals.
It is widespread across a huge variety of habitats.
It is beautifully camouflaged.
It has extraordinary sensory abilities.
Its venom is remarkably complex.
It is an efficient ambush predator.
And it has adapted remarkably well to a world increasingly influenced by humans.
But perhaps the most interesting thing about the fer de lance is the relationship it has with people.
It doesn't need to chase us.
It doesn't need to attack us.
It simply lives its life in the same tropical landscape that we are exploring.
Sometimes that landscape belongs to the snake first.
So when you are walking through Panama's forests, farms and jungle trails, keep your eyes open, especially around your feet. Watch where you put your hands. Be particularly careful around dense vegetation, logs and areas with lots of rodents.
And if you see that unmistakable triangular head sitting quietly among the leaves, admire it from a safe distance.
Because the fer de lance is one of Panama's most impressive animals.
It is also one of the few where the old jungle rule really does make sense:
Look before you step.